CHAPTER 2
Wind Energy
Expected Outcomes
Assess the technical feasibility of selecting and siting a single wind turbine. Components and
characteristics of wind turbines, wind turbine aerodynamics.
Wind Energy 2
What is Wind Energy?
Winds are produced by the uneven heating of the atmosphere by the
sun, and earth rotation. Wind flow patterns are changed by the
vegetation, water bodies, and earth's terrain. Wind energy or wind
power describes the process by which the wind power is extracted
from air flow using wind turbine to generate mechanical energy or
electrical energy. Mechanical energy can be used for specific tasks
(wind pump for pumping water and sails).
Mechanics of wind
• Pressure force
• Coriolis force
• Intertial force
• Frictional force
Wind Energy uses
Wind energy use is about 2% of the domestic energy
consumption
Expected to increase to about 20% over next two decades.
Denmark is the world leader
- produces wind power over 20% of the country’s power
.
Types of Wind energy:
1.- Planetary winds
2.- Local winds.
.
Planetary
winds are cause due to greater
heating of earth’s surface near the equator
as compared to solar heating near the north
& south poles.
Local winds due to the local change of
temperatures in coastal areas and these are
also caused due to uneven heating in
mountains along the slopes.
Wind Turbines
http://energy.gov/eere/wind/how-does-wind-turbine-work
12/19/2015
KidWind Project | www.kidwind.org
12/19/2015
How Wind Turbines Work
Wind turbines operate on a simple principle. The energy of the wind
turns propeller-like blades around a rotor. The rotor is connected to
the main shaft, which spins a generator to generate electricity. Wind
turbines are mounted on a tower to capture the most energy. A blade
acts like an airplane wing. When the wind blows, a pocket of lowpressure air forms on the downwind side of the blade. The lowpressure air pocket then pulls the blade toward it, causing the rotor to
turn. This is called lift. The lift force is much stronger than the front
side of the blade wind force, which is called drag. The combination of
drag and lift causes the rotor to spin like a propeller, and the rotating
shaft spins a generator to generate electricity.
Wind Turbine Types
http://www.cbmjournal.com/content/
2/1/8/figure/F2?highres=y
12/19/2015
.
 Two types of Modern wind turbines:
the horizontal-axis, like the old-style farm
windmills used for water pumping, and
the vertical-axis.
Wind Turbine Size and Power Ratings
Wind turbines are available in a
different sizes.
The largest turbine has blades that
span more than the length of a cricket
field, hight 20 building stories, and can
power 1,500 homes with electricity.
.
A small sized wind machine: rotors size
between 10 and 25 feet in diameter
30 feet Height and can provide the
power of home or small industry.

.
 In this system the wind energy is
converted to DC power by a DC generator &
power the batteries.
Total wind power
The total wind power is equal to the incoming kinetic energy of the
wind stream.

P=⅛ ρD²C³
P=power
ρ=Density of air(kg/m³)
D=Rotor diameter
C=Incomming wind
velocity(m/s)
Offshore wind power
Construction of wind farms in water bodies to produce electricity. Offshore wind
power generate higher electricity compare to on land because of stronger offshore
wind power.
Economics and benefits:
Offshore wind power can help to reduce air pollution, meet renewable electricity standards
reduce energy imports, and greenhouse gases and create local business and jobs chances.
economically viable
A report from a association of researchers from diffrent universities,
government and industry, places out several things needed in order to
bring down cost of the offshore wind power plant to make more
economically feasible:
Improving wind performance models with new designs.
 Less weight of turbine materials
Reducing problematic gearboxes
By controlling's of turbine load and strategies
To minimize typhoon and hurricane by new designs of turbine and
rotor
Advantages and Disadvantages of WindGenerated Electricity
Renewable and Clean source of energy.
 No greenhouse gases from wind plants.
Cost and Intermittence
The pros and cons of wind power are still the subject of heated debate. There
are two main arguments against wind power:
 High cost to produce wind power than the conventional electricity.
Wind power is irregular because winds are uncontrollable and
unpredictable.
Environmental Concerns
 Noise pollution by the rotor blades,
aesthetics impacts, and birds having
been killed by flying into the rotors.